Biological Sciences 300/301, Smith College | Neurophysiology
Schedule, Spring 2009
http://www.science.smith.edu/departments/NeuroSci/courses/bio330/syllabus.html
UPDATED: April 28, 2009
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DATES
Note: Neurophysiology will not be offered in Spring 2010. It will be offered in Spring 2011.
TOPICS AND ASSIGNMENTS
Jan 27-29
2009
ELECTRICAL SIGNALS IN NEURONS.
Neurons convey information: sensory receptors for touch.
Rapidly-adapting (phasic) vs. slowly-adapting (tonic)
responses.
Code: bigger stimulus = more frequent action potentials.
Case discussion: How real is sensory reality?
Example: crustacean muscle receptor organ (MRO or
"stretch receptor").
Intracellular recording using microelectrodes.
Electrical potential. Ohm's Law.
Resting, generator and action potentials.
Link between amplitude of generator potential and frequency
of action potentials.
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Our textbook is on reserve in the Science Library, as is another textbook by John Dowling that offers a simpler version of the topics we discuss in class. Course requirements and other Administrative Information are available online. Additional assignment: Sign up for the class wiki as the Main Author for one class, and as an Editor for other classes. The Wiki is hosted at http://bio300.pbwiki.com/. The necessary password will be announced in class. |
Brains and identified neurons.
An overview of some brains and neurons. Sections through
the mammalian brain.
CNS of arthropods as a comparison. Structure of ganglia.
Visualizing individual neurons: inject fluorescent dye or
dense marker; cobalt backfill; HRP backfill; lipid-soluble
dyes; immunocytochemistry; green fluorescent protein.
|
Reading: PNS4, Chapters 1 and 2
for general review. Figures for next Tuesday's weekly quiz : 2-10, Table 2-1, 21-8, 21-9, 21-10. |
Lab 1: Using the oscilloscope.
Feb 3-5
MEMBRANE POTENTIALS
NOTE: The first weekly quiz will be on Tuesday, February 5, at the start of class.
Ions, pumps, and membrane potentials.
Squid giant axon. Distribution of ions in axon and blood. Na/K pump: active transport of ions.
Case discussion: Why do red blood cells need pumps?
Forces acting on ions. Equilibrium between diffusion and electical attraction. Equilibrium potential. Nernst equation.
Ions that can cross membrane carry charge until cell's potential matches the ion's equilibrium potential. Concentrations can be regarded as constant. Preview of the action potential.
Membrane channels for Na+ and K+ ions.
Voltage clamping: command and measured potentials;
inject current as needed to maintain constant
conditions.
Axon: early inward current and late outward current follow
depolarization.
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View the five videos on the squid giant axon. Figures for next week's quiz: 7-1 to 7-4, 9-2, 9-3. |
Lab 2: Circuits and amplifiers.
Feb 10-12
Voltage clamping (continued).
Separating currents due to Na ions and K ions (low-Na, TTX, TEA). Na-inactivation.
Case discussion: A lethal shipboard snack.
Calculating conductance for each ion. Peak conductance vs. potential. Peak current vs. potential.
Reconstructing the action potential from voltage-clamp
data. Threshold and refractory period.
Na/K pump is not a direct part of the action potential
mechanism; it just "cleans up" afterward.
Patch clamping to look at individual channels.
Propagation of the action potential.
Local circuit currents.
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Figures for next week's quiz: 9-4 to 9-10, 9-12, 6-2 to 6-8, 8-1, 8-4 to 8-6, 8-8 (skipping equivalent electrical circuits), 4-17, 4-18. NOTE: Tuesday, Feb 17: Part 1 of our exam on membrane potentials in place of a quiz. |
Lab 3: Effect of potassium concentration on the resting potential.
Feb 17-19
Propagation (continued).
Local circuit currents. Length constant. Conduction velocity. Strategies for faster conduction: giant fibers and myelination. Demyelinating diseases.
Case discussion: The case of the missing channels.
Generator channels. Other voltage-dependent channels.
"Generator-type" channels: not electrically excitable. Examples: stretch-activated channels. Reversal potential suggests which ions go through the channels.
Initiation of action potentials at nearest low-threshold site.
Calcium and potassium channels (IA, IC) that modulate firing rate of neurons.
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Figures for next week's quiz: 8-4 to 8-6, 8-8, 4-17, 2-10, 9-11. |
No lab (Rally Day).
Feb 24
Molecular structure of voltage-dependent channels.
Physiological insights to structure of excitable channels (pore size, TTX binding at selectivity filter, pronase attack on inactivation gate).
Solving the molecular structure of a bacterial K channel. Location of selectivity filter.
Purification of Na channel protein, sequencing of gene. Deductions about structure and function. S4 helix is the activation gate. Location of inactivation gate.
Structure of Ca channel is similar to Na channel.
|
Videos on K channel structure. No quiz next week (Exam Part 2 instead). |
Lab 5: Computer simulations of action potentials and synaptic potentials. (Note change in sequence.)
Feb 26
SYNAPSES.
Electrical synapses: structure of gap junctions, examples of electrical conduction.
Neuromuscular
junction
Structure of pre- and post-synaptic components.
EXAM Part 2: in class on Tuesday, March 3, covering
work through February 24.
A copy of last
year's exam is available online (PDF
file,
*Smith
campus only).
Mar 3-5
Presynaptic release
of vesicles. Endplate potential. "Minepps." Quantal release
(vesicles).
Release requires depolarization, entry of extracellular
calcium through excitable Ca-channels.
Timing and synaptic delay.
Post-synaptic receptors for
acetylcholine.
Molecular structure: 5 homologous subunits. Patch clamping:
selectivity for small positive ions.
ACh degradation: acetylcholine esterase. Synthesis: choline acetyl transferase. Reuptake and repackaging in vesicles via transporters. Pharmacology of the neuromuscular junction.
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Figures for next week's quiz: 10-1 to 10-7, 11-1 to 11-15, 14-3 to 14-8, 14-12. |
Lab 4: Action potentials in earthworm giant axons.
Mar 10-12
Neuron-to-neuron synapses:
spinal motoneurons.
Temporal and spatial summation.
Excitatory synapses. EPSPs. Reversal potential impies Na and
K ions involved.
Transmitter: glutamate. AMPA and NMDA subtypes of glutamate
receptor
Inhibitory synapses, IPSPs. Reversal potential = Cl
ions.
Transmitter: glycine and GABA. Receptors structurally
similar to AChR.
Interaction of excitation and inhibition = synaptic
integration. Weighting of synapses by location.
Transmitters activating second messengers (metabotropic receptors).
Classical ionotropic (fast) vs. metabotropic receptors
(slow).
Three groups of metabotropic second messengers.
Example: autonomic nervous system.
Pre- and post-ganglionic neurons. Parasympathetic and
sympathetic innervation of heart. Multiple transmitters
create PSPs of different durations (sympathetic
ganglion)
Mechanisms of action: collision-coupling to channels, second messengers causing phosphorylation of channels, opening or closing channels.
Modulation at synapses: lobster neuromuscular junction, hippocampal slice. Multiple second-messenger systems, overlapping pathways, pre- and post-synaptic modulation.
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Figures for next week's quiz: 12-1 to 12-5A, 12-8 to 12-16 (epsp/ipsp); 10-8, 13-2 to 13-5, 13-7 and 13- 8, 13-10 and 13-11, 13-15, 13-18 (2nd messengers); 49-5 and 49-6 (autonomic n.s.). |
Lab 6: Electroretinogram of the crayfish eye.
Mar 14-22
Spring break
Mar 24-26
GENERATING MOVEMENT.
Levels of control: within muscle cells (graded depolarization and calcium levels). Control at the motor unit (firing frequency and recruitment).
Feedback from spindles and Golgi tendon organs.
Central control of posture and locomotion: command interneurons in crayfish, central pattern generators for locomotion in Tritonia, crayfish, roaches and cats. Role of sensory feedback in CPGs.
Case discussion: Swimming blindly (based on your response papers -- see the Special Assignment below).
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Special Assignment: Write a response
paper on two readings (TBA) about generating
behavior, due in class March 27. Write one
paragraph on each of the following questions: Figures for next week's quiz: 34-2 to 34-5, 34-8 to 34-12 (motor unit); 36-2, -3, -6 and -9 (reflexes); 37-1, -4, -6, and -7 (locomotion). |
Lab 7: Motor units in the crayfish nerve cord.
Mar 31-Apr 2
VISION.
Eye and retina. Visual pigments. Responses of photoreceptors to light.
Case discussion: How feasible are retinal implants?
Synaptic network in the retina. Center-surround receptive fields of bipolar cells.
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Figures for next week's quiz: 26-2 to 26-6. |
Lab 8: Discussion: Crayfish swimmeret system. A paper is due (in lab) on the crayfish swimmeret system (see lab instructions).
Apr 7-9
Visual processing by bipolar cells and retinal ganglion cells. Transient (Y) and sustained (X) ganglion cells.
Visual pathway: Spatial distribution of ganglion cells. Pathway to lateral geniculate nucleus and visual cortex. Simple cells in striate cortex.,
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Special Assignment: MacRetina simulation exercise (due in class April 14). Figures for next week's quiz: 26-7, 26-9, 27-1, 27-4, 27-6, 27-11 to 27-13. View video about Hubel and Wiesel's experiments. |
Lab 9: Projects: Crayfish swimmeret system.
Apr 14-16
Primary visual cortex. Complex and end-stopped ("hypercomplex") cells. Spatial frequency selectivity.
Cortical anatomy: Ocular dominance columns, orientation pinwheels, layers, blobs.
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Figures for next week's quiz: 27-14 to 27-18. |
Lab 10: Projects.
Apr 21-23
Extrastriate cortex: Pathways for motion and form. Dorsal pathway, area MT, direction and disparity selectivity.
Inferotemporal cortex: Ventral pathway to inferotemporal lobe. Objects and faces. Visual perception.
Case discussion: Signaling by a face-selective neuron.
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Reading: PNS4, pages 548-569 (motion and form), 492-505 (perception). There is no quiz next week, but the following figures are important ones in this week's reading: 28-1, 28-6, 28-7, 28-9 to 28-13, 28-16 to 28-19; 25-9, 25-12. Special Assignment: Paper on top-down components of visual processing. (See handout.) The paper is due in class on Thursday, April 30. |
Lab 11: Projects.
Apr 28-30
Color vision: retina, LGN, V1. Color patches and blobs. V4: color constancy.
Discussion: an advanced problem in visual processing. (Packet of readings, with a writing assignment)
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Reading: PNS4, pages 572-583 (color). |
Lab 12: Project poster presentations. (See Lab 9 for assignments and due dates.)
May 5-8
Final exam (self-scheduled). A copy of last year's final exam is available online. (PDF files, *Smith campus only).
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